<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        *{
            font-size: 20px;
        }

        .a{
            background-color: antiquewhite;
        }
        #b{
            background-color: aqua;
        }
        div,p{
            border: 2px solid black;
        }
        div p{
            font-size: 25px;
            font-family: "楷体";
            border: 2px solid red;

        }
        a:link{
            background-color: green;
        }
        a:visited{
            background-color: blue;
        }
        a:active{
            color: black;
        }
        a:hover{
            background-color: white;
        }
        p::first-letter{
            color: brown;
        }
        p::first-line{
            background-color: aqua;
        }
        div>p{
            background-color: bisque;
        }
        div+p{
            font-size: 30px;
        }
        p~ul{
            background-color: green;
        }
    
    </style>
</head>
<body>
    <div class="a">ddddd</div>
    <div id="b">dddddd</div>
    <p>pooo00000000<br>0000</p>
    <div>
        <p>p0000<br>0000</p>
        <ul>ulllllll</ul>
        <a href="https://www.baidu.com/">main超链接</a>
    </div>

</body>
</html>